Droplet actuators are used to conduct a wide variety of droplet operations. A droplet actuator typically includes two substrates separated to form a droplet operations gap. The substrates include electrodes for conducting droplet operations. The gap between the substrates is typically filled with a filler fluid that is immiscible with the liquid that is to be subjected to droplet operations. Droplet operations are controlled by electrodes associated with one or both of the substrates. There is a need for droplet actuator devices, techniques and systems for making and using droplet actuators. There is a need for devices, techniques and systems for preparing samples and/or reagents for loading onto a droplet actuator; for loading samples and/or reagents onto a droplet actuator; for storing samples and/or reagents on a droplet actuator and/or for use on a droplet actuator; and/or for conducting droplet operations using samples and/or reagents on a droplet actuator. There is a need for devices, techniques and systems for conducting flow through bead handling and washing. For example, there is a need for techniques for splitting droplets in a flow-through system, compartmentalizing beads in droplets in a flow-through system, and washing droplets in a flow-through system. There is a need for droplet actuator devices, techniques and systems for making and using droplet actuators to process viscous, solid or semi-solid samples. For example, there is a need for a techniques for processing process viscous, semisolid, and/or solid samples. There is a need for droplet actuator devices including a gel for use in gel electrophoresis, along with techniques and systems for conducting gel electrophoresis on a droplet actuator. There is a need for a fluidics system and technique for using the system for loading liquids onto a droplet actuator. There is a need for droplet actuators loaded using the fluidics system and method of the invention and methods of using such droplet actuators to conduct droplet operations. There is a need for droplet actuator devices, techniques and systems for processing samples for use on a droplet actuator device. There is a need for droplet actuator devices, techniques and systems for capturing, concentrating and/or eluting nucleic acids; and sensitively isolating nucleic acids using one or more droplet operations to perform separation protocols. There is a need for kits including droplet actuators of the invention along with various other components suitable for executing the techniques of the invention, such as reagents, sample collection devices, and/or instructions.